Electronic denier control



April 27, 1954 J. s. SENEY ELECTRONIC DENIER CONTROL 5' Sheets-Sheet 1Filed June '7, 1950 INVENTOR.

JOHN s. SENEY ATTORNEY p 27, 1954 J. s. SENEY 2,676,495

ELECTRONIC DENIER CONTROL Filed June 7, 1950 5 Sheets-Sheet 2 WESYONMETER INVENTOR. JOHN- 5. SENEY A TTORNEY April 27; 1954 J. 5. SENEY ,4

ELECTRONIC DENIER CONTROL Filed June '7, 195Gv 5 Sheets-Sheet'3INVENTOR.

JOHN S. SENEY A TTORNEY April 27, 1954 .-.l. s.- SENEY ELECTRONIC DENIERCONTROL 5 Sheets-Sheet 4 Filed June 7, 1950 EIDEIUD INVENTOR JOHN S.SENEY ATTORNEY April 27, 1954 J. s. SENEY ELECTRONIC DENIER CONTROL 5Sheets-Sheet 5 Filed June 7, 1950 INVENTOR.

JOHN S. SENEY m7 ATTORNEY Patented Apr. 27 1954 ELECTRONIC DENIERCONTROL John S. Seney, Henrico County, Va., assignor to E. I. du Pont deNemours and Company, Wilmington, Del., a corporation of DelawareApplication June 7, 1950, Serial No. 166,750

This invention relates to an improved speed control for spinningmachines, such as viscose rayon spinnin machines, to produce finishedyarn of more uniform denier. More particularly, this invention isconcerned with the spinning of viscose rayon on a bobbin spinningmachine and with an electronic control of the machine drive shafts toefiect improved results.

In the manufacture of regenerated cellulose yarn by the viscose process,provisions are made for varying the rate of draw-off and/or pump de-"livery to produce in its finished form a yarn of more uniform denier anddyeab-ility than could be provided in the absence of these correctivechanges. In the bobbin spinning process as the yarn cake builds up andthe peripheral lay of the yarn becomes greater and greater, therotational speed of the bobbin must be diminished. Because of variationsin shrinkage that arise throughout the bobbin package this diminution inrotational speed should be other than a straight line compensation andnumerous me chanical arrangements have been proposed and used withvarying degrees of success.

The mechanical compensators used are dem pendent on constant speed drivemotors and generally the pump shaft speed is assumed to be at a constantR. P. M. and the pump delivery therefore constant, whereas there aresometimes variations of as much as 5% in the spinning solution deliveryand not infrequently denier variation in the finished yarn may be asmuch as 7% above or below the stated denier or an overall variation asmuch as 14%.

' It is, therefore, an object of this invention to provide more accuratecontrol of the driving elements to maintain the denier more nearlyconstant and to provide means for compensatively altering the rate ofyarn draw-off should variations in pump delivery arise. Other objectswill be apparent from the description that follows.

/ The objects of this invention are accomplished by synchronizing thebobbin speed and pump speed plus the desired speed variable included onthe cam through the use of an electronic circuit in which changes inbobbin speed are made to effect proportional changes in pump speeds, orvice versa. Briefly, this invention is accomplished by having in abalanced or balanceable relationship two tachometer generators or onetachometer generator and a constant voltage source of direct currentelectricity e. g. a battery. Where two tachometer generators are usedone is directly connected to the bobbin drive shaft and one is directlyconnected to the pump shaft 5 Claims. (Cl. 74-395) and so wired andcontrolled through a cam operated variable resistance that the desiredproportional speeds of these two shafts are maintained. The electricalconnections and details of construction and operation are shown indrawings listed below and explained hereinafter. While the invention isdescribed with particular reference to viscose spinning, the apparatuscan be applied to the spinning or extrusion of any synthetic yarn.

In the drawings:

Figure 1 is a flow sheet showing the control apparatus of this inventionin simplified form;

Figure 2 is a detailed electrical wire diagram of'the control apparatusshown in Figure 1;

1 Figure 3 is a side elevation of the cam operated variable speedcontroller;

Figure 4 is a plan view of the apparatus shown in Figure 3 and Figure 5is taken on line 55 of Figure 3.

Referring to Figure 1, G-I is a tachometer generator attached to thbobbin shaft drive (connection not shown) and G4 is a tachometergenerator attached to the shaft driving the viscose pump or pumps(connection not shown). These generators are connected so that thenegative connection H1 is common to each. The voltage output of eachgenerator is proportional to the speed of the shaft to which each isconnected and in'the electrical circuit shown no current fiows when theoutput of the generators is the same.

Connected in parallel with generator (3-! are resistance potentiometersR-2 and R-B. A highly accurate indicator for tachometer G-l is providedas follows:

As shown in Figure 1, a bias voltage is obtained from REC-l, a seleniumrectifier, and this D. C. voltage is applied across R-9. The negativeconnection of REC-l is connected to the common negative terminal ill ofG-l. The slider All of R-9 can then be set to produce the necessaryexact biasing voltage to the tachometer indicator M-l. A resistor R-3 isconnected across the output of (3-! so that any ratio of the voltagedeveloped by G-l can be obtained between the slider 50 of R-3 and thecommon negative terminal 10 of G-I. Connected between slider 50 of R-3and the tachometer indicator M-l is a variable series resistor R4. Thisprovides a fine adjustment to the tachometer indicator. To illustrate,assume G-l is turning R. P. M. and slider 50 at R-3 is set midway of R-3and slider 40 at R-9 is so adjusted that M-l reads 0 R. P. M. If G-l isspeeded up to 200 R. P. M., it will show full scale of the tachometerindicator meter provided R4 has been properly set for this particularmeter movement and the meter M-I will show only speeds above 140 R. P.M. and no more than 200 R. P. M. Meter M-l has a scale which will bemagnified in increments of 1 R. P. M. between the speeds of 140 to 200B. P. M.

The output of 6-! is connected across potentlometer R-2 and that of G-2is connected across the resistor R-5. Resistor R-2 is the high speedcontrol voltage divider and it applies the desired voltage from G-I toinput transformer T4. Resistors R- and R8 are connected in series andshunt the slider contact Ill of R-G to the common negative junction 18of G-l and G-2. The resistors R-5, R-6 and R-B control the voltageoutput from G-2 to transformer T-A, Transformer T4 has dual input andbetween it and the electrical bridge comprising R-5, R-6 and R4 is aconverter CON-| which is a single pole double throw switch operating insynchronism with the line voltage furnished by T-l 8-! throughconnections X--Y (see Figure 2). This switch is polarized by a permanentmagnet, so that one of the contacts will always be closed during thenegative half cycle of the supply voltage from 8-,! T1 and the othercontact will be closed during the positive half cycle. Any flow ofcurrent .due to a difference in potential between slider contact 20 ofR-2 and 35 of 3-8 is converted from direct current to ,a proportional.60 cycle alternating current by the converter CON-l and transformer T-d.

Transformer T-4 a ts as a phase shifting and coupling device between thebridge circuit and the electronic vol age amplifier 80. 'lhe phase ofthe output voltage at 6 depends on the polarity of the voltage fromsliders 20 and 35 at R-2 and R43, respectively. After conversion, the A.C. Voltage Output is amplified by a conventional electronic amplifierhook-up 80 (shown in detail in Figure 2). The motor MOT-3 is a two phasecontrol motor. It is a brushless, reversible, variable speed inductionmotor of the drag cup type. MOT-3 is connected, as described below, tothe control screw 91 or the bobbin drive P. I. V. (se Figure 4). P. I.V. is the generally accepted designation for a positive-drive,infinitely variable sp ed changer, one type being disclosed in U. S.Patent No. 2,076,202 at page 2, column 1, line 60. Depending upon theamount of voltage and the polarity of the current, MOT-3 changes thespeed of the bobbins and since tachometer generator C i is attached toit, it changes also thespeed of G-l. and the amount of its output.

In order to control denier or mass per unit length of the yarn spun, theamount of viscose or other spinning solution must be taken into account.As stated, tachometer generator G-Z is attached directly to the meteringpump shaft (not shown) of the spinning machine and fur,- nishes voltageto one side of the network. The slider contact 3!] at R 8 is operated bycam 35. The movement of cam 35 is controlled by synchronous motor MOT-l,which drives this cam on the electronic circuit or, when this is off,mechanically operates the P. I. V. control screw. The compensatingvoltagev coming from R-8 is then changed as required. From this, it canbe seen that the ratio of yarn windup to pump delivery will at all timesstay constant, provided the cam is made for straight line compensation.

vThe electronic circuitcan'be seen in more; detail by reference toFigure 2 and to the iiollo wfns d si n. W t ge erators Gel nd.

4 connected as shown and turning at a given speed and with slidercontact 2c of R-2 set at a certain point, a voltage, for example, 1volt, is obtained between the negative common connection 10 and theslider contact 29 of R4. The slider contact I!) of R-fi is set to obtaina positive potential of 1 volt between it and the common negativeconnection it. If slider contact 30 of R 8 is set at the extreme upperposition as shown in Figure 1, the 1 volt potential is also obtained atthe contact 36. With a 1 volt potential at contact 20 and at contact 30,no current would flow between these points. If the speed of a generator,say G-i, changes for example, from 1 volt to 2 volts, there would exista difference in potential and current would flow between contacts 20 and30.

This current is converted to 60 cycle A. C. by CON! and transformer T-4.Ihe A. C. voltage output is amplified by a conventional electronicamplifier hook-up through tubes V-I, V-2 and power amplifier V-3. ,Theamplifier is supplied direct current from rectifier tube V4 and 5-2 T-lThe amplified current is supplied to MOT-3 by power amplifier tube V-3.The other motor winding is continuously energized by line voltage from8- 1 T4. The phase of the current coming from V-3 determines thedirection of rotation of MOT-3 and its amplitude determines the Speed ofthe motor.

With 6-2 turning at a constant rate to produce 1 volt between in and 30and G-j now pro: ducing 2 volts, the slider 20 at R-2 becomes of apositive polarity and the slider 31] of a negative polarity. In view ofthe negative voltage, MOT-3 will rotate in a direction to slow down thebobbin because it is driving the control screw of the bobbin P. I. V.Since G-I. is attached to the bobbin drive, MOT-3 will operate in theslow down direction until the voltage difference between the sliders at20 and 30 is elimi: nated. At this point the entire network is inbalance.

If G-! produced a smaller voltage than G-2, say 0.5 volt, a differenceof 0.5 volt would exist between sliders 20 and 30 of the oppositepolarity. Slider 30 at R-8 would be plus and slider 20. at 3-2 would benegative in polarity. MOT-3 would run in a reverse direction raising thespeed of the bobbins and, hence, G-l until zero voltage difierence againwas attained. Thus, if the speeds of G-l and G4 are not the same, MOT-3will bring about the change needed to keep the network in balance.

With this in mind R5 is sov adjusted that a voltagedrop is eifectedacross R-8 equal to the desired speed change of G-l or the bobbin wind.-up speed. Assuming that G-I, develops ,2 volts at 200 R. P. M. and 1.5volts at R. P. M., 3-5 is so adjusted that 0.5 volt is the drop acrossR-B. The voltage at slider lil of R-G will be set to produce 2 voltsbetween it and the common negative connection. With the above statedconditions the voltage between the sliders 20 at R-2 and 3d at 11-8 willbe 0. provided that G.- -l is turning 200 R. P. M. Now if slider 3c ismovedv from its top position (Figure 1) so that it is at the other endof R43, there will be a voltage. d'iiierehce of 0.5 volt. In order forthere to be- 0. volt between sliders 2e and 30, G-l will have to turn atl50 R. P. M. Since MOT-3 keeps the: voltage'between sliders 3D and Illat Q. then by changing the position along resistance R- 8.-of ts. s id rhe obb n s ed ca be cha ed from 20,0 R. P. M. to 150713.33. At the startof the. spin-,cycle beforev the bobbins begin to build up yarn, G- -2will be generating 2 volts. If for some reason it does not rotatesufficiently to do this, but say 1.99 volts, MOT-3 reduces the speed ofG-I or the bobbins so that G-I produces only 1.99 volts.

The movement of contact an to vary the resistance of R-B involves amechanical unit containing certain electrical switches which relate themovement of contact to thechange needed to keep the network in balanceover the desired speed pattern. This unit is shown in Figures 3, 4 and5.

The entire unit is mounted on a frame 41. Shaft 4 is a drive shaftconnected to the bobbin drive P. I. V. by sprockets and chain 5. A plateor support member 2 is mounted so that it can pivot about shaft 4. Thisplate 2 has attached to it gears I'I, I8, 38, I3, 39 and cycle cam 35,cam follower 36, and slider 30 in contact (not shown, see Figure I) withR-8. The unit 88 bolted toplate 2. supports cam follower 36, rack 42,gear 45 and one end of spring 86.

.Mounted on the stationaryframe. 41 is shaft 63..which is connected toand driven by MOT-3, the electronic control motor. 63 is gear I6 whichdrives gear I8 when the latter is in the position shown. Gear I8 in turndrives gear. I1. Since gear I I-is. attached to shaft 4 which in turn isattached to the bobbin P. I. V. control screw, shaft 63 driven by MOT-3controls the bobbin P. I. V. drive or the speed at which the bobbins aredriven.

Also mounted on frame 41 is shaft 64 which is driven by cycle timermotor MOT-I. This drives gear I2 which in. turn drives gear i3 (mountedon pivotable. plate 2) when gear I3 is in the position shown in Figure5. Gear I3 drives gear 38 through gear 39 and gear 38 drives cycle camin a clockwise direction. As this cam rotates it moves cam follower 36,which bears roller 31 resting on the periphery of cam 35, in anoutwardly direction. Cam follower 33 has on one side a rack, designatedas 42 in Figure 5. This rack turns gear which is attached to slidercontact 30 and the resistance at R-8 is changed accordingly. Thus, MOT-4drives cam 35 which through cam follower 36 changes the compensatingvoltage coming from R-8.

At the start of anew spinning cycle the operator turns reset switchactuator 54 to the reset position and holds it there until the machineis set to high starting speed. MOT-2 starts up driving shaft 62 andsince plate 2 is connected to it by shifter link 93, plate 2 is made topivot around shaft 4. As plate 2 moves switch actuator 34 eventuallycauses microswitch B to open and this stops MOT-2 and keeps it stoppedas long as the operator holds the reset switch actuator 54 in the resetposition. The pivoting of plate 2 to this reset position has caused gearIt to go out of mesh with gear I6 and gear I2 to go out of mesh withgear I3. The speed reset hand wheel 55 attached to shaft 4 is free toturn and the operator turns it to set the bobbin speed at the start ofthe spinning cycle or 2 0 R. P. M. Cam reset spring 23 also causes cam35 to return to the start position; cam stop 28 comes back to rest onthe stop or shock absorber 29 (see Figure 4). Slider 30 of R-8 isreturned by spring 86 to its start position. Now the machine has beenreset and the operator allows reset switch actuator 54 to assume itsnormal position. This by-passes switch B and MOT-2 starts up again; thebearing 2 pivots so that the gears mesh momentarily and then go out ofAttached to shaft 6. mesh and it continues to pivot until microswitch Ais opened. This stops MOT-2. Gears I6 and I8 now mesh as do gears I2 andI3. MOT-3 is now driving the control screw to the P. I. V. and thetiming motor MOT-I is advancing the cycle cam 35 through itscompensating cycle.

vIn addition to the foregoing, provision may be made to reduce thebobbin speed automatically by a straight line speed reduction by MOT-Iin the event of failure of the electronic system. This is doneautomatically by having connected, as shown in Figure 2, between thesliders 30 at Rr-8 and 2!! at R-2 a sensitive, normally-open relay (JR-4which is connected and set to close if more than 2 micro amperes flowbetween the sliders of R8 and R-2 (indicating that the electronic systemis failing because current in this circuit should always be near zero ifthe system is in balance).

Assuming that the electronic control is'failing and CR-4 has closed itscontrol contacts, circuit is made from the line voltage neutral throughthe closed contact of CR4 to trip out warning light L-5 and to coil of(JR-2 through normally closed contacts of reset switch G to the otherside of the line. v This, of course, energizes (JR-2 openingcontacts-Band 5 of (IR-2 and closes 5 and 4. This reverses timer motorMOT-I. Contacts I and 2 of CR-2 open and 2 and 3 close. This appliesline voltage through normally closed reset switch G through contacts 2and 3 of (JR-2 through normally closed switch C to reset motor MOT-2 tothe other side of the line. Reset motor MOT-2 starts up and shifts plate2 so that gears I2 and IS engage thus connecting the P. I. V. controlscrew with timer motor MOT I whereby MOT-I reduces the bobbin speed at aconstant rate. Limit switch C is opened by pin 94 thereby st0p' pingMOT-2 with gears I2 and I8 in mesh. CR-3 is provided to energize CR2when the electronic control unit is removed from service for repair; Theswitch C is a normally closed switch and is operated .by pin 94 which iskeyed to MOT2 and is fixed to open switch 0 when gears I8 and I2 are inmesh or when (MOT-I is in control of the drive. A jumper is installed inplugs P-I2A and PI2-I2 which keep CR-3 energized as long as these plugsar in place. The removal of either will de-energize (JR-3 therebyenergizing CR-2, placing the compensator on straight line compensation.Thus, if the electronic control fails for some reason, the rotationalspeed of the bob-- bins will be diminished in accordance with the: cakebuild-up. 3 I

Upon. the resettingof CRf-4, CR-Z drops out again reversing MOT-4energizing MOT-2 through reset limit A. Plate 2 then opens reset limit Awhen gears I6 and I8, and I2 and I3 are again in mesh. .When the resetswitch is operated, current flows to reset motor MOT-2 from normallyclosed contacts of reset switch F (see Figures 2 and 3) through dofflimit switch B thus running MOT2 until B contact is opened by actuator34 attached to plate 2. In this position gears are neutralized for thereset and upon the release of reset switch to MOT2, witch G again closesand starts MOT-2 so that the proper gearing is again engaged at gears I6and I8 and at gears I2 and I3. If relay CR-Z is energized the P. I. V.will be operated from the timer motor MOT-I. If CR-Z is dropped out, theP. I. V. will be driven from the electronic control motor MOT-3.

In order to prevent CR-4 closing while the machine is being reset arelay CR-I is energized by caveats the voltage applied to the dottingri'oil ='motor. KThi *motor must be running "during the :dofii'ngoperation but-it is= turned off as soon -as the ma chine is reset andrestrung.) The normally closed contacts opened by "CR-I "disconnect therelay CR4 from the system thus preventing its accidental action duringthe reset operation. In order to prevent the P. I. V. control screw rrombeing turned past its -limits, limits'witches E aJnd Dareeonn'ected inseries with the supply voltage to MOT-'3 1 and MOT- i In some instances,as for "example, in bucke't spinning or even "bobbin processes, aconstant voltage supply such as a battery may housed in place of G 2.Itis, of' course reoogiiized that the draw-off device-maybe awindu'psuch as a zbobb'hi or :it may be simply "a roller-such as algodet.

By 1 means of this invention excellent uniform ity in yarn denier isobtained. The Variation in denieris-n'o more than it of 1 percent or ch1 200- denier yarn i3 denier, which makes the yarn admirably-suited forany purpose. In the case of fine denier yarn,s'uchas 100 denier,the'normal variation resulting from this control is scarcely measurablebeing of theorder of A denier.

While the invention has been described in terms of denier controL'itmay, of course, "be used in connectionwith any sort of desiredcompensation. Fox-instance, to improve dyeing 'um'i'ormity throughout"the spin package or to produce :ya'rn having greater uniformity in anyone prop'erty or abetter average uniformity of a numiber o'f properties, such as-elon'gation, tenacity or other physicall rpropertiesthat may be affected advantageously by altering the proportional "rateof spinning solution delivery and yarn draw-off.

The invention is applicableto any type of spinhing machine such asbucket or yarn advancing reel collections-or other continuousyarn'production methods as well as the bobbin collection method. It maybe used to advantage not only with regenerated cellulose yarn producedby the viscose process but also any coagulating bath spinning process orto dry spun or melt s un yarns of any'description. Forexampleycuprammonium cellulose yarn, cellulose ester yarns, celluloseether yarns, polyvinyl yarns, such as polyvinyl chloride, polyvinylacetate, 'polyactrylonitrue, nylon, polyester yarn, etc..

Any departure from the procedure described herein which conforms to theprinciples of the invention is intended to be included within the scopeof the claimsbelow.

I claim:

1. Apparatus for controlling the'speed of one driven shaft relative tothe speed "of a "second independently driven shaft which "comprises apair of tachometer generators connected in series opposition andarranged to be driven respectively at speeds proportional to the speed"of said' first shaft'and the speed of said second shaft, are sistancenetwork connected to receive the uni- 8 directional output ofsaid-generators, an amplifi'er circuit including converter "means"respon- "'si-v'e to amplitude and direction of flow of current insaidresistance network for providing an alternating current output signal ofproportional magnitude andof a phase related "to the polarity ofsaidoutput, and speedcontrol'me'ans responsive to the output signal of saidamplifier and adapted to vary'the relative speeds of said shafts inaccordance with said magnitude and phase until said outputs'ign'al isnu'llified'as the result of corresponding changes in the speeds 'of saidgenerators.

2. Apparatus as defined in claim -1 in which said speed control meansincludes a reversible, variable speed induction motor connected to acontrol screw of a positive-infinitely-variable drive connected to oneof saidshafts.

Apparatus as defined claim 1 in which a resistor in said resistancenetwork is continuousi-y adjusted by a cam driven by a cycle time motor,thereby varying said output signal and causing the relative speeds ofsaid shafts to change as afunctio'n of time in'a predetermined manner.

4. in apparatus for controlling the speed of one=drlven shaft relativeto 'thespeed of a 'second independently driven shaft by the action of amotor adapted to change the speed'ratio of said shafts .in response toan error signal derived through an electrical control circuit fromtachometer generatorsconnected in series opposition and arranged tobedriven atspeeds proportional to the respective shaft speeds, theimprovement comprising relay means responsive to an excessive value ofsaid-"error signal indicative of abnormal functioning of said=controlcircuit and operative to disconnect saidmotorand to replace it bymeans'for reducing the speed of said first shaitgradually until :itstops to prevent uncontrolled driving of said first shaft.

5. The apparatus improvement defined in claim 4 in which said firstshaft is driven through a positive-infinitely-variable drive having acontrol screw and the means for reducing the speed of "said shaftcomprises a timer motor connected to said screw to rotate it so as toreduce the speed'of said shaft at a constant rate.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1 1,926,275 FitZGEIald v Sept. 12, 1933 2,076,202 Lewellen Et'al Apt. 6, 1537 2,314,332 "Kline- Sept. 10, 1940 2,237,985 Garman Apr.8, 1941 2,306,157 Edwards at al Dec. 22, 1942 2,325,331 Edwards et alJuly 27, 1943 2,437,972 'schmitz Mar. 16, 1948 2,454,731 Burkholder Nov.23, 1948 2,583,074 Aubert 'et a1. Jan. 22, 1952

